Apparatus for continuously rolling steel

ABSTRACT

A CONTINUOUS STEEL ROLLING MILL APPARATUS. BETWEEN EACH PAIR OF A PLURALITY OF ROLLING MILLS ALONG THE ROLLING LINE IS PROVIDED AN ADJUSTING ROLLING MILL. A SMALL CAPACITY D.C. MOTOR IS COUPLED TO EACH ADJUSTING MILL AND SUPPLIES ONLY SUFFICIENT POWER TO THE ROLLS THEREOF TO OVERCOME THE INERTIA AND BEARING FRICTION. AN ADJUSTING DEVICE IS PROVIDED ON EACH ADJUSTING ROLLING MILL FOR ADJUSTING THE SCREW DOWN POSITION IN RESPONSE TO THE CONDITION OF THE MATERIAL BETWEEN THE ROLLING MILLS. THE ADJUSTING ROLLING MILL PERFORMS LIGHT LOAD ROLLING FOR CONTROLLING THE TENSION AND THE THRUST ACTING ON THE ROLLED MATERIAL SO THAT IT IS EITHER SMALL OR ZERO, THEREBY ELIMINATING BAD EFFECTS ON THE SECTION OF THE ROLLED MATERIAL. DETECTING MEANS CAN BE PROVIDED FOR DETECTING THE TENSION AND THRUST ON THE MATERIAL BETWEEN THE ROLLING MEANS, SUCH DETECTING MEANS BEING COUPLED TO THE ADJUSTING DEVICE FOR SETTING THE SCREW DOWN POSITION IN RESPONSE TO THE DETECTED CONDITION.

. Jan. 19, 1971 YAMATA YOSHINO ETAL 3,555,862

APPARATUS FOR CONTINUOUSLY ROLLING STEEL Filed Jan. 24, 1969 FIG. I

FIG. 3

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' K m w47z INVENTORS j Bwwflkzw ATTORNEYS United States Patent 3,555,862APPARATUS FOR OUSLY ROLLING Yamata Yoshino, Kanichi Kishikawa, andKatsuyoshi Tanaka, Kitakyushu, Japan, assignors to Nippon SteelCorporation, Tokyo, Japan, a corporation of Japan Continuation-impart ofapplication Ser. No. 554,447, June 1, 1966. This application Jan. 24,1969, Ser. No. 814,869

Int. Cl. B21b 37/00 U.S. C]. 72-10 3 Claims ABSTRACT OF THE DISCLOSURE Acontinuous steel rolling mill apparatus. Between each pair of aplurality of rolling mills along the rolling line is provided anadjusting rolling mill. A small capacity DC. motor is coupled to eachadjusting mill and supplies only suflicient power to the rolls thereofto overcome the inertia and bearing friction. An adjusting device is provided on each adjusting rolling mill for adjusting the screw downposition in response to the condition of the material between therolling mills. The adjusting rolling mill performs light load rollingfor controlling the tension and the thrust acting on the rolled materialso that it is either small or zero, thereby eliminating bad effects onthe section of the rolled material. Detecting means can be provided fordetecting the tension and thrust on the material between the rollingmeans, such detecting means being coupled to the adjusting device forsetting the screw down position in response to the detected condition.

This application is a continuation-in-part of application Ser. No.554,447, filed June 1, 1966, now abandoned.

This invention relates to an apparatus for continuously rolling steel,particularly large-sized cross-section steel shapes.

So far dilficulty has been encountered in continuously rolling steel,particularly with respect to large sized crosssection steel shapes, andcontinuous rolling has not yet been generally practiced except for steelbillets.

In the continuous rolling of steel, it is desirable to equalize thedelivery volume per unit time of the rolled material delivered from therolls of each rolling mill; and in order to obtain a uniform shape ofrolled products, it is best to keep the rolled material free fromtension and compression when it is running between two rolling mills.However, in the conventional continuous rolling method, it is difiicultto equalize the delivery volume per unit time of the rolled material,because the rolling factors change during the operation. It is widelyknown that for comparatively thin sheet steel and also comparativelysmalldiameter steel bar (including wire rod), the continuous rolling ofthese materials has been effected by intentionally forming a loop, andadjusting the number of rotations of the motors of the rolling mills.But large-sized materials cannot make a loop as does thin sheet andsmall bar, because they have a great moment of inertia of the crosssection and will not bend or loop easily; and, moreover, ma terialshaving a section of complex shape tend to be deformed when subjected tobending into a loop, and also they sometimes are introduced to theinduction apparatus at the inlet of the rolling mill, not in the normalcourse, but offset therefrom. Even in a rolling operation usingcompression in an amount which does not cause an enlargement of thesteel material, the exclusive use of a rolling mill of the conventionaltype causes a great impact on the rolled materials when they are passedbetween rolls and also causes trouble between the rolls and theinduction apparatus when an enlargement occurs. So tensionrolling hasbeen generally used in place of the above type rolling. However, intension-rolling, the cross-section of the rolled material tends to becontracted so that waving and contraction of the rolled material occursin the longitudinal direction of the material.

As mentioned above, in the continuous rolling of largesizedcross-section steel shapes, neither compression nor tension on therolled material is desirable, but because unfinished steel rolled from abillet must subsequently be subjected to processes including a finishingrolling before it is a finished product, the continuous rolling isworthwhile in order to raise efficiency at the sacrifice of uniformityof product quality. However, for the above reasons, wholly continuousrolling of large-sized steel materials has been thought to be difficult,and therefore it has not yet been practiced.

On the other hand, in order to conduct non-load rolling which will notproduce tension or thrust on the rolled material, there is available amethod, according to which any force Working on the rolled material isdetected and the rotation of the rolls is controlled in response to suchdetection. However, this method is impractical because it is unreliablein operation and in large scale equipment due to the inertia of rotationof the rolls which makes quick response impossible. As a result, a largecapacity motor is required to allow for over-load operation in a shorttime and a large size rolling mill is necessary to Withstand the strongforces produced during operation.

Likewise the method of adjusting the screw down position of the rollingmill in response to the detection of forces working on the rolledmaterial, which is conducted in the same way as mentioned above, is notpractical for the reason that it necessitates altering the screw downposition of all the rolling mills subsequent to the rolling mill inquestion.

As mentioned above, the continuous rolling of steel, particularlylarge-sized steel materials, has been thought to be highly eflicient,but has not yet been put into practice because of a number ofdifficulties.

For the purpose of solving these difficulties, it is an object of thisinvention to provide a continuous rolling apparatus which consists of anumber of rolling mills set close to each other in the rollingdirection, and therefore is generally considered to be a whollycontinuous rolling apparatus, such apparatus making possible continuousrolling of large-sized cross-section steel shapes as well as large-sizedsteel billets or blooms without producing such strong tension or thrustthat the section of the rolled material is affected and also withoutusing any precise device for controlling the motors for the rollingmills.

Another object of this invention is to provide an adjusting rolling millwhich can be set between each two rolling mill stands in the rollingapparatus consisting of a plural number of rolling mills, thereby makingpossible equalizing the delivery volume per unit time of the rolledmaterial released from the rolls and controlling tension or thrust whichwould affect the section of said rolled material, such adjusting rollingmill being driven by a small motor and having an adjusting device foradjusting the screw down position thereof.

The invention will now be explained in greater detail in connection withthe accompanying drawings, in which:

FIG. 1 is a plan view of the rolling apparatus according to thisinvention;

FIG. 2 is an enlarged sectional elevation of a part of the apparatus ofFIG. 1 showing an example of a control circuit for adjusting for theelfects caused by thrust on the rolled material; and

FIG. 3 is a front elevation showing of the adjusting rolling mill ofthis invention having a pair of rolls driven by a small capacity D.C.motor.

According to the present invention, in a continuous steel rollingapparatus consisting of a plural number of rolling mills driven by largecapacity motors for rolling mills, there is set between each twoadjacent stands of the rolling mills adjusting rolling mills which aredriven by a small capacity D.C. motor but are not given a rolling actionat all, and which have an adjusting device for adjusting the screw downposition. These adjusting rolling mills are small-sized rolling millswhich are driven with only enough power sufficient to overcome theinertia of rotation of the rolls and the friction between the rolls andthe bearing and with insufficient power for rolling. Each of theadjusting rolling mills is equipped with a pair of rolls of smaller sizethan the rolls of the rolling mill stands and also with a device forfinely adjusting the screw down position. By driving these smaller sizerolls just enough to overcome bearing friction and inertia, the effectof the impact of the steel being rolled on the smaller size roller willbe substantially eliminated.

This invention relates to a continuous steel rolling apparatus which ischaracterized as above and which has means for detecting tension andthrust on the material being rolled between said rolling mills, and forsetting the screw down position in response to such detection, therebyconducting light load rolling on the rolled material contrary to thetension and thrust, resulting in control of the tension and thrustworking on the rolled material such that it is zero or so small that nobad effects will be produced on the cross-section of the rolledmaterial.

The following is an explanation of this invention with reference to theattached drawing. In the drawing, 1, 2 and 3 are the rolling mills eachhaving a pair of rolls driven for rolling the material to be rolled andwhich are driven by respective motors 5, 6 and 7 for the rolling millswhich supply rolling power to the rolling mills 1, 2 and 3,respectively. Pinion stands 10, 11 and 12 are provided for the rollingmills 1, 2 and 3. The motors 5, 6 and 7 are synchronous motors formaking the respective rolling conditions constant. Adjusting rollingmills 8 and 9 are positioned between adjacent rolling mills, each havinga pair of small-sized rolls which are driven by a conventional smallcapacity D.C. motor, but not supplied with power for rolling. The smallcapacity DC. motors 13 and 14 supply a pair of the small-sized rolls 17and 18 attached to the rolling mills 8 and 9 only with power sufiicientto overcome the inertia of rotation and the friction between the rollsand the bearings, but not with any substantial power for rolling. Inpractice they can be as small as 100 kw., depending on the size of theshape being rolled. Conventional D.C. speed control means can be used tocontrol these motors.

On the other hand, the continuous rolling apparatus of the conventionaltype is composed only of the rolling mills which have their rollssupplied with power for rolling, similar to the rolling mills such asthe adjusting rolling mills 8 and 9. In the drawing of this invention, 4is the rolled material and the arrow points in the rolling direction.FIG. 2 shows the cross-section of the upper roller 15 and the lowerroller 16 of the rolling mill 1 which are supplied with power forrolling and a cross-section of rolls 17 and 18 which are not suppliedwith power for rolling, and the cross-section of the upper and lowerrolls 27 and 19 of the rolling mill. Adjusting devices 20 (FIG. 3) forsetting the screw down position of the upper roll 17 in the rolling millare connected to a motor 21 for setting the screw down position. Thestand 22 for the rolling mill 8 has bearing boxes for the rolls 17 and18. The rolling mill stand 22 is set firmly on a sole-plate 23 which isinstalled on the foundation.

In the operation of the above apparatus of this invention for rollingsteel material 4 in the direction of the arrow, there is applied to therolled material a strong force in the horizontal direction which isproduced by the friction and rolling pressure between the upper roll 15and the lower roll 16 respectively and the rolled material, which forceworking in the horizontal direction is utilized to cause said rolledmaterial 4 to be rolled between the small-sized rolls 17 and 18 whichare not provided with power for rolling. In other words, the light loadrolling by the rolls 17 and 18 is such that the rolled material is notsubject to impact caused by insertion and is thus not damaged thereby.By properly setting the reduction rates of the rolls 17 and 18 which aresupplied only with power sufiicient to overcome the inertia of rotationand the friction of the bearings of the rolls and which are driven bythe small capacity D.C. motor capable of nearly equalizing the speed atwhich the rolled material 4 is supplied and the circumferential speed ofthe rolls at nonload operation, the force working in the horizontaldirection on the rolled material 4, and constituting the motion forrolling by said rolling mill, will not become stronger in proportion tothe enlargement of the rolled materiol 4.

The load cells 24 and 24' are positioned beneath the the rolling mill 2subsequent, in the direction of rolling, to the small-sized adjustingrolling mill 8. Because of tension and thrust produced on the rolledmaterial 4, moment is produced centering around the lower port of saidrolling mill 2, which is converted to electric current, which, in turn,is relayed to a value setter 25 to obtain the deviation, which isaltered to a value for setting the screw down position through theconverter 26 to be finally relayed to the small capacity D.C. motor forsetting the screw down position by means of motor 21. This is aconventional technique.

Similarly, if tension exists between the rolling mills 1 and 2, therolling mill 2 will lean to the left, making the load cell 24 start towork and changing the load to electric current, finally putting themotor for setting the screw down position 21 into operation to changethe screm down position lower. Thus, the rolled material coming from thesmall-sized rolling mill 8 is made thinner and thus extended to belonger, so that the tension between the rolling mills 1 and 2 is reducedor eliminated.

As mentioned above, the continuous rolling apparatus of this inventionhas many great advantages. If this is used for rolling large shapes, itwill produce many satisfactory results which could not be obtainedotherwise.

We claim:

1. A continuous steel rolling mill apparatus for rolling large steelsections, which comprises a plurality of rolling mills spaced from eachother along a line, an adjusting rolling mill at a fixed positionbetween each pair of rolling mills, a small capacity D.C. motor coupledto each adjusting rolling mill supplying only sufficient power to therolls thereof to overcome the inertia and bearing friction thereof, andan adjusting device on each adjusting rolling mill for adjusting thescrew down position in response to longitudinal forces exerted by thematerial, whereby light load rolling is performed on the rolled materialrunning between said rolling mills, and the tension and thrust acting onthe rolled material is controlled so as to be nothing or so small thatno waving or contraction will be produced on the section of the rolledmaterial.

2. An apparatus as claimed in claim 1 wherein the adjusting rolling millis a small-sized rolling mill consisting of a pair of rolls of smallerdiameter than those of each of said rolling mills.

3. A continuous steel rolling mill apparatus as claimed in claim 1further comprising detecting means for detecting the tension and thrustproduced between said rolling mills and coupled to said adjusting devicefor setting the screw down position of said adjusting rolling mill inresponse to the condition detected.

1/1944 Shayne et al 72-234 3/ 1967 Motomatsu et a1. 72-21 MILTON S.MEHR, Primary Examiner U .8. Cl. X.R. 72234

